/*
Copyright 2023 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package protocol

// Copy from https://github.com/aws/aws-sdk-go
// May have been modified by Beijing Volcanoengine Technology Ltd.

import (
	"strings"

	"k8s.io/autoscaler/cluster-autoscaler/cloudprovider/volcengine/volcengine-go-sdk/volcengine/request"
)

// ValidateEndpointHostHandler is a request handler that will validate the
// request endpoint's hosts is a valid RFC 3986 host.
var ValidateEndpointHostHandler = request.NamedHandler{
	Name: "volcenginesdk.protocol.ValidateEndpointHostHandler",
	Fn: func(r *request.Request) {
		err := ValidateEndpointHost(r.Operation.Name, r.HTTPRequest.URL.Host)
		if err != nil {
			r.Error = err
		}
	},
}

// ValidateEndpointHost validates that the host string passed in is a valid RFC
// 3986 host. Returns error if the host is not valid.
func ValidateEndpointHost(opName, host string) error {
	paramErrs := request.ErrInvalidParams{Context: opName}
	labels := strings.Split(host, ".")

	for i, label := range labels {
		if i == len(labels)-1 && len(label) == 0 {
			// Allow trailing dot for FQDN hosts.
			continue
		}

		if !ValidHostLabel(label) {
			paramErrs.Add(request.NewErrParamFormat(
				"endpoint host label", "[a-zA-Z0-9-]{1,63}", label))
		}
	}

	if len(host) > 255 {
		paramErrs.Add(request.NewErrParamMaxLen(
			"endpoint host", 255, host,
		))
	}

	if paramErrs.Len() > 0 {
		return paramErrs
	}
	return nil
}

// ValidHostLabel returns if the label is a valid RFC 3986 host label.
func ValidHostLabel(label string) bool {
	if l := len(label); l == 0 || l > 63 {
		return false
	}
	for _, r := range label {
		switch {
		case r >= '0' && r <= '9':
		case r >= 'A' && r <= 'Z':
		case r >= 'a' && r <= 'z':
		case r == '-':
		default:
			return false
		}
	}

	return true
}
